Cincinnati -- Novel semiconductors produced in the University
of Cincinnati College of Engineering are highlighted on the cover
of this month's Materials Research Society Bulletin.

The opto-electronic device literally lights up the
university's "double horseshoe" logo using gallium nitride doped
with the rare earth elements such as erbium, europium and
thulium. Together, the wide range of colors nearly duplicates or
exceeds the spectrum produced by tube technology and television.

"If you want to have full color, three-color displays based on
semiconductor technology instead of tubes ... If you want flat
panel displays, this will take up less space and use much less
power," said Andrew Steckl, Ohio Eminent Scholar and Gieringer
Professor in electrical and computer engineering at UC.

Steckl's Nanoelectronics Laboratory recently received a $1
million grant from the National Security Agency to develop
photonic devices which can store and process more information
more quickly. A previous grant focused on the telecommunications
aspects of photonics.

Both projects require the use of multiple techniques for
producing the next generation of semiconductors. Steckl said
batch processing is fine for mass producing simple chips, but
developing the technology for the new semiconductors required MBE
(molecular beam epitaxy) and integrating the circuitry required a
FIB (focused ion beam) technology.

"Ions have energy, mass, and charge, so they're the most
versatile," said Steckl, explaining why ion beams are preferred
over virtually massless electrons and photons which are typically
used to make semiconductor devices. "You can use both their
energy and their momentum, and you can manipulate them."

In addition, you can customize your chips by changing
conditions during processing, which cannot be done with
conventional technology. That takes more time, an acknowledged
disadvantage of beam technology, but Steckl says the flexibility
is demonstrating that FIB and other beam technologies have a
future as bright as his opto-electronic devices.

"If I just wanted to make large numbers of the same transistor
or laser or waveguide, then I wouldn't need it," admits Steckl.
"But I want to make a working circuit. Here, I design a laser,
here a waveguide...to that I may add an amplifier or a divider or
a combiner or a detector, and so on. Each of these components is
going to have different requirements, so that is the problem.
We're trying to address how to integrate them. FIB and MBE are
two of the keys to solve this problem."

Most important, photonics allows better integration between
chips and from board to board. Traditional microelectronics is
limited by the number of connections to avoid wires short-circuiting each other.

"Wires cannot cross, so electrical signals sent by wire have
this limitation in terms of their density," explained Steckl.
"Optical signals can cross, so you can go with much, much higher
density. Photonic components are the ideal components for these
interconnects."

The ultimate research goal is to develop a storage system
which can handle one terabyte of storage with processing times in
micro- to nanoseconds. Although Steckl isn't certain of the
ultimate applications by the National Security Agency, he does
foresee many other applications for his devices.

"Commercial uses?," asks Steckl. "My guess is 'Yes.' The
government tends to develop the most challenging applications,
because their needs are the most difficult. Some form of that
technology generally hits the commerical marketplace and really
pushes the technology. That's why it's important to have federal
R&D support."

The full-color possibilities of the rare earth-doped
semiconductors are also likely to have applications in the
medical field. "In biology and medicine, you sometimes need a
specific light color or multiple colors to get a clear diagnosis,
or trigger a biochemical reaction, or evaluate a biological
system and get an unambiguous picture," said Steckl.

Other materials produced in Steckl's UC laboratory emit light
in the infrared, a key wavelength for telecommunications. "We
have yellow and orange too. We're constantly working on this and
having great fun coming up with devices which emit light in
various combinations of colors."